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Screening for oesophageal cancer

Oesophageal cancer is a common cause of cancer related death in the world. The prognosis in the advanced stages is unfavourable, but the early oesophageal cancers are asymptomatic and curable, and usually go undetected until they have spread beyond the oesophageal wall. Endoscopy with iodine staining or cytologic examination are two common screening tests for early oesophageal cancer. These screening tests were started in the 1970s, but the true benefit is inconsistent and is uncertain due to lead-time bias, which is the amount of time by which the diagnosis is advanced by the screening procedure; and length-time bias, where screening is more likely to detect slow-growing disease rather than altering the person's duration of life. This review intended to determine the efficacy of the two screening tests for oesophageal cancer. We identified 3482 studies but none were RCTs of screening. Several non-comparative studies showed that the screening tests may increase the incidence of reported oesophageal cancer and improve the survival results after a screening test, but these results could indicate bias rather than a true causative effect. Therefore, there is a strong need for randomised controlled trials (RCTs), especially long-term RCTs, to determine the efficacy, cost-effectiveness, and any adverse effects of screening for oesophageal cancer.

Authors' conclusions:

There were no RCTs that determined the efficacy of screening for oesophageal cancer. Non-RCTs showed a high incidence and the reported better survival after screening could be caused by selection bias, lead-time and length-time biases. RCTs are needed to determine the efficacy of screening for oesophageal cancer.

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Background:

Oesophageal cancer is a global heath problem. The prognosis for advanced oesophageal cancer is generally unfavourable, but early-stage asymptomatic oesophageal cancer is basically curable and could achieve better survival rates. The two most commonly used tests are cytologic examination and endoscopy with mucosal iodine staining. The efficacy of the screening tests is controversial, and the true benefit and efficacy of screening remains uncertain because of the potential lead-time and length-time biases. This review was conducted to examine the evidence for the efficacy of screening for oesophageal cancer (squamous cell carcinoma and adenocarcinoma).

Objectives:

To determine the efficacy of early screening, using endoscopy with iodine staining or cytologic examination, in reducing mortality from oesophageal cancer in asymptomatic individuals from high-risk and general populations.

Search strategy:

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 8), The Cochrane Library (2012, Issue 8), MEDLINE (1950 to August 2012), EMBASE (1980 to August 2012), Allied and Complementary Medicine (AMED) (1985 to August 2012), Chinese Biomedical Database (CBM) (January 1975 to August 2012), VIP Database (January 1989 to August 2012), China National Knowledge Infrastructure (CNKI) (January 1979 to August 2012), and the Internet. We also searched reference lists, conference proceedings, and databases of ongoing trials. There was no restriction on language or publication status in the search for trials.

Selection criteria:

We included only randomised controlled trials (RCT) of screening versus no screening for oesophageal cancer. Randomisation of groups or clusters of individuals was acceptable.

Data collection and analysis:

Two review authors independently scanned the titles and abstracts from the initial search for potential trials for inclusion. We did not find any trials that met the inclusion criteria.

Main results:

The electronic search identified 3482 studies. Two authors independently reviewed the references. The reports of 18 studies were retrieved for further investigation. None met the eligibility criteria for a RCT investigation of the effects of screening versus no screening for oesophageal cancer.

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